1. Field of Use
This invention relates to analytical methods for quality control in the selection of hydroxy-terminated polybutadiene polymers from commercial lots thereof and to products resultant from practice of these methods. This invention, more particularly, relates of predicting how the aforementioned commercial lots will function in crosslinked net works by an examination of the microstructures of the hydroxy-terminated polybutadiene materials prior to incorporation in such networks.
2. Prior Art
Hydroxy-terminated polybutadiene polymers find wide industrial application. When crosslinked, they can form part of a matrix useful as a rubbery binder in propellants, coatings, composites and the like. As a consequence, diverse grades of hydroxy-terminated polybutadiene are available on a commercial scale.
The nature of hydroxy-terminated polybutadiene is often critical in obtaining desired properties of the end product in which the crosslinked polybutadiene serves as a matrix or binder material. The need for special hydroxy-terminated polybutadienes ordinarily is met by testing various grades thereof and selecting the grade or grades particularly suited to give the matrix its desired properties.
In certain instances, however, it has been discovered that this selection process is inadequate for consistently predicting which hydroxy-terminated polybutadienes will function appropriately. In particular, it has been discovered that use of hydroxy-terminated polybutadiene sold under the same tradename unexpectedly gives crosslinking matrices of variable strain properties, even when the hydroxy-terminated polybutadiene identically performs in standard analytical tests. As a result, considerable expense is incurred when products derived from this hydroxy-terminated polybutadiene do not meet specifications.
It would be desirable, therefore, if there were a simple test which could distinguish between commercial lots of hydroxy-terminated polybutadienes sold under the same name such that their performance could be predicted with unqualified assurance.
In this regard, and in accordance with this invention, it has been discovered that (a) hydroxy-terminated polybutadiene produced commercially by seemingly the same process (i.e., catalysis with hydrogen peroxide) may sometimes contain nearly indetectable amounts of epoxy functionality and (b) use of hydroxy-terminated polybutadienes having above a certain amount of such epoxy functionality can impart significantly lower strain capacity to the crosslinked matrices resulting from their use as compared to use of those hydroxy-terminated polybutadienes having below such amount of the epoxy functionality.